The present invention relates to a dock leveler with run-off barrier configuration. A dock leveler is a device designed to bridge the gap between a loading dock and the surface of a truck or trailer bed. Under most circumstances, the floor of the truck bed and the top of the loading dock are at unequal heights and most dock levelers known in the prior art can accommodate some degree of vertical range of mis-match in these elevations.
There are three main categories of dock levelers, namely, pit levelers, vertically stored levelers, and edge of dock levelers. Pit levelers are designed to reside in a formed pit in the dock and are usually designed to accommodate a comparatively large height mis-match between the top surface of a loading dock and the surface of a truck bed, as much as 12 inches or more in some cases. Pit levelers provide unobstructed access to the dock and tend to be more expensive to manufacture and install than other types of dock levelers.
Vertically stored levelers do not require as much concrete work when they are installed and can often accommodate as great a height mis-match as is the case with a pit leveler. The vertically stored leveler has severe shortcomings in that it is extremely expensive to install and with a vertically stored leveler in place, access to the dock face is unobtainable.
A third type of dock leveler is known as the edge of dock leveler and attaches to the face of the dock where it intersects with the surface of the dock. Edge of dock levelers are more economical to install than other types of levelers in that less concrete work is required and in a similar manner as a pit leveler, edge of dock levelers provide unobstructed access to the dock as desired such as for end loading of a truck. However, edge of dock levelers known in the prior art do have a limitation in that, as known, they have a limited ability to accommodate a severe height mis-match between the dock surface and truck bed surface, usually, no greater than around 5 inches.
Edge of dock levelers as they are known in the prior art typically consist of three primary components, the faceplate, the deck and the lip. The faceplate is stationary and solidly fixed to the dock face. The deck rotates around the faceplate, and the lip rotates around the opposite end of the deck. When stored, the deck is substantially horizontal and the lip is angled approximately 90 degrees with respect to the deck hanging downward by gravity. To use such an edge of dock leveler, the deck is rotated back engaging a mechanism readies the lip for extension. The deck is then rotated forward and the engaged mechanism causes the lip to rotate around the deck. The now extended edge of dock leveler rests on the truck bed creating the bridge for loading and unloading of the truck. As the lip rests on the truck bed, the mechanism disengages. To return the edge of dock leveler for another use, the deck is rotated back some amount and the lip falls. After the lip falls off the truck bed, the deck is rotated forward until it rests in the initial cycle orientation. If the truck pulls away from an extended edge of dock leveler, the leveler will fall back to the initial, stored configuration.
Edge of dock levelers are also known to employ other activation mechanisms. Often a counterbalance spring or counterweight mechanism is installed to lessen the force required to activate the leveler. Other methods include powering the unit with hydraulics, pneumatics, and/or electromechanical power. On both ends of a typical edge of dock leveler, bumpers are often provided that prevent a truck from impacting the leveler when in the stored position.
Usually, when stored, both pit levelers and edge of dock levelers provide unobstructed access to the dock. Sometimes this can be advantageous, such as when a truck is loaded to the extreme rear not allowing room for the lip of the leveler to rest on the truck bed. But often, the unobstructed access provided by traditional storage position of both prior art pit levelers and prior art edge of dock levelers can allow equipment to run off the dock. A dock is typically around 3xc2xd feet off the ground and free fall from that distance can easily cause equipment damage, personal injury, or even death.
One type of edge of dock leveler has been mandated by the U.S. Postal Service for use on their loading docks and is often described as the xe2x80x9cPost Office Modelxe2x80x9d. In such a device, the lip may be extended into the deck forming a short, nearly vertical barrier when the edge of dock leveler is in the stored position. This configuration prevents lightly loaded equipment such as, for example, postal carts, from running off the edge of the dock. One deficiency of the so-called xe2x80x9cPost Office Modelxe2x80x9d is the fact that it does not have a stored position allowing unobstructed access to the dock surface. In particular, the closest thing to a stored position for the xe2x80x9cPost Office Modelxe2x80x9d consists of the position in which it comprises a light capacity vertical barrier.
The following prior art is known to Applicant:
U. S. Pat. No. 3,486,181 to Hecker, Jr. et al. teaches a dockboard including a deck and a lip. In the stored position of the device, the lip is received between two plates. In that position, the deck portion is aligned in a common plane with the surface of the dock.
U. S. Pat. No. 3,636,578 to Dieter discloses a spring counterbalanced compact dockboard including a deck and a lip pivotably mounted together. Dieter does not teach any configuration in which the device may act as a barrier.
U. S. Pat. No. 3,974,537 to Ellis et al. teaches a lip extender for loading dock levelers that includes a deck and a lip pivotably mounted together including a toggle arm connected between the dock and the lip allowing the lip to drop onto the truck bed. Ellis et al. fail to teach a pivotable linkage having an over-center stop mechanism combined with a kick-out bar.
U. S. Pat. No. 4,065,824 to Ellis et al. teaches similar structure.
U. S. Pat. No. 4,665,579 to Bennett et al. teaches a counterbalancing mechanism for an edge-of-dock dockboard. Bennett et al. fail to teach or suggested a configuration in which their device may be used as a barrier.
U. S. Pat. No. 4,525,887 to Erlandsson et al. teaches a counterbalancing mechanism for the ramp of a dockboard. The Erlandsson et al. device includes only a short lip and does not include the over-center structure of the present invention.
U. S. Pat. No. 4,689,846 to Sherrod teaches a dock leveler apparatus including a deck and a lip pivotably mounted together. Sherrod fails to teach or suggest use of the device as a barrier nor does he teach the specific details of the linkages of the present invention.
U. S. Pat. No. 4,920,598 to Hahn discloses a dock leveler with automatic vehicle barrier. In Hahn, a device separate from the deck and lip may act as a vehicle barrier. This differs from the teachings of the present invention in which the deck and lip may be reconfigured to create the barrier. U. S. Pat. No. 5,040,258 to Hahn et al. is similar in that a structure separate from the deck and lip is employed as a vehicle barrier.
U. S. Pat. No. 4,935,979 to Walker et al. discloses a dock leveler operating apparatus in which the dock leveler includes a deck and a lip pivotably mounted together. A linkage such as a chain interconnects a leg pivotably attached to the deck. Walker et al. fail to teach or suggest use of their device as a barrier nor do they teach or suggest the linkages disclosed herein.
U. S. Pat. No. 5,157,801 to Alexander teaches a dock leveler having an automatically actuated vehicle barrier. In a similar manner to the Hahn patents, the vehicle barrier in Alexander consists of a structure that comprises a separate device from the structure and function of the deck and lip.
U. S. Pat. No. 5,195,205 to Cook discloses a dock leveler operating apparatus in which a handle is used to actuate the functions of the dock leveler. Cook fails to teach or suggest a configuration of the deck and lip thereof that operate as a barrier nor does he teach the other linkage instructions of the present invention.
U. S. Pat. No. 5,311,628 to Springer et al. discloses a dock leveler with an improved automatic material handling vehicle barrier. As is the case in Hahn, Hahn et al. and Alexander, the vehicle barrier of Springer et al. is a separate structure from the structures of the deck and lip. The same can be said of the teachings of U. S. Pat. No. 5,333,339 to Larsen.
U. S. Pat. No. 5,343,583 to Cook discloses a run-off guard and dock leveler locking apparatus. In Cook, in the run-off guard position, the lip is left unsupported. This differs from the teachings of the present invention.
U. S. Pat. No. 5,452,489 to Gelder et al. discloses a dock leveler with automatic end barrier. In Gelder et al., the end barrier is incorporated in a structure separate from the deck and lip. U. S. Pat. No. 5,457,838 to Gelder et al. teaches similar structure.
U. S. Pat. No. 5,553,343 to Alexander teaches a dock leveler with folding barrier lip. In Alexander, a configuration is provided in which the lip may be supported on a bracket. However, the barrier structure is separate and apart from the deck and lip.
The present invention relates to a dock leveler with run-off barrier configuration. The present invention includes the following interrelated objects, aspects and features:
(1) In a first aspect, the inventive dock leveler includes a faceplate, a deck, and a lip. The faceplate, as is customary, is mounted on the end of a dock. The deck is pivotably mounted to the faceplate and the lip is pivotably mounted to the deck.
(2) The deck is pivotably mounted to the faceplate via a pivotable interconnection comprising a first linkage including two legs pivotably mounted to each other as well as to each of the faceplate and the deck.
(3) The faceplate and the lip are interconnected with a pivoting connection comprising a second linkage including two arms pivotably connected together and pivotably connected to each of the faceplate and the deck, respectively. The second linkage includes structure allowing the arms to go to an over-center configuration but with a limit stop mechanism limiting the degree of pivoting in the over-center configuration.
(4) The faceplate may include one portion extending horizontally over the surface of the dock and a further portion depending vertically over the front face of the dock. Gusset means preferably comprising two gussets are provided on the second portion of the faceplate that extend outwardly therefrom and include recesses terminating in upwardly turned detents or fingers. In one configuration of the inventive dock leveler, the termination edge of the lip may be received within the recesses in the gussets so that the deck portion thereof acts as a sturdy barrier.
(5) The over-center feature incorporated into the legs interconnecting the faceplate and the lip allows the inventive dock leveler to be pivoted to a position in which the legs achieve the over-center configuration whereupon pivoting of the deck in the opposite direction causes the inventive device to extend outwardly and into engagement over the surface of a truck bed. In the event this procedure is carried out and a truck bed is not sufficiently close enough to the lip to capture it thereover, a kick-out device is incorporated into the undersurface of the deck to release the two legs from their over-center position allowing the lip to collapse downwardly to its stored configuration.
(6) In an alternative construction, an actuating lever may be mounted under the deck and having an interconnection with the second portion of the faceplate via a flexible connector such as, for example, a chain or cable.
As such, it is a first object of the present invention to provide a dock leveler with run-off barrier configuration.
It is a further object of the present invention to provide such a device in which, in one configuration thereof, it may act as a secure run-off barrier.
It is a still further object of the present invention to provide such a device in which an over-center mechanism allows easy extension of the deck and lip thereof over the surface of the bed of a truck or other vehicle.
It is a still further object of the present invention to provide such a device which may easily be operated merely through insertion of a lightweight handle in a recess provided therefor.
These and other objects, aspects and features of the present invention will be better understood from the following detailed description of the preferred embodiments when read in conjunction with the appended drawing figures.